Page 365 - My FlipBook

VARIOUS KINDS OF GOLD IN COMBINATION. 363

face on which it is packed, as shown by the cross lines on the filling, a,
Fig. 343, which are reproduced from those made in the cavity shown
at b in Fig. 343. The lines across the bottom of the cavity were made
with the sharp point of a hatchet excavator.
This form of gold can be used to advantage, sometimes, at the cervi-
cal wall of compound cavities, provided a matrix has been tightly ad-
justed. For starting fillings in approximal cavities in the front teeth it
is sometimes invaluable, and it can be used in conjunction with any other
form of gold, or interchangeably. If at any point in a filling the oper-
ator sees a place where he thinks he can put a piece of plastic gold
better than any other, there is no reason why he should not use it.
Sometimes it is particularly useful to thrust into soft foil to make a sur-
face upon which to build cohesive foil. It can be packed with either
Jiand or mallet force, and with smooth or serrated instruments.
(B) Non-cohesive and Cohesive Gold.—Strictly speaking, non-
cohesive gold cannot be made coliesive by annealing, and can be used
only on what is known as the " wedge " principle. " Soft gold," as the
term is generally understood, is non-cohesive when used without anneal-
ing, but when annealed it becomes cohesive.
Softness and toughness are the qualities necessary to make tight joints
between fillings and cavity walls, and good preparations of non-cohesive
and soft golds have these qualities. Consequently, a method that Mill
admit the use of these golds against cavity walls with a sufficient amount
of cohesive gold added to insure strength and hardness, when strength
and hardness are necessary, is desirable.
An exaggerated illustration of stopping a cavity watertight with soft
or cohesive gold is that of stopping a bottle tightly by using a velvet
<;ork or a piece of hickory. It can be done with the hickory, but the
time required to do it perfectly, as compared with doing it with the
velvet cork, is not unlike the difference between making a filling of soft
and one of cohesive gold.
Simple cavities, whether in occlusal or approximal surfaces, can often
be half or two-thirds filled with soft gold in a very few minutes, and
the rest of the cavity filled with cohesive gold. A filling made in this
manner is as good as, or even better than, one made entirely of cohesive
foil, and the time required to do it is much less, as the soft gold can, on
account of its softness, be used much faster than can the cohesive. In
cavities of easy access the soft gold can be so manipulated as to be
against the walls of the cavity at every point. Small cylinders, or any
other form of soft gold, can be set around the edges, and the central
portion of the cavity filled with cohesive gold. Care must be taken to
•carry the cohesive gold into the soft with instruments not too large, so
that a mechanical union between the two golds is effected, as but little